| 1/2 cup butter 1/2 cup vegetable oil 1 3/4 cups white sugar 2 eggs 1/2 cup sour milk 1 teaspoon vanilla extract 2 cups sifted all-purpose flour 1 teaspoon baking soda | 1/2 teaspoon ground cinnamon 1/2 teaspoon ground cloves 1/2 teaspoon salt 4 tablespoons unsweetened cocoa powder 2 1/2 cups grated zucchini 1/4 cup ground walnuts 1/4 cup semisweet chocolate chips |